1. Field of the Invention
The present invention relates to a detachable plug assembly for retaining a pipe in an external unit such as a hose fitting or hydraulic unit, and more particularly to an assembly wherein a bushing mounted on the pipe has at least one circumferential groove into which there engages, in mounted condition, a locking element mounted on the external unit which prevents unintended loosening of the connection.
2. Description of Related Art
DIN 74 234 and DIN 74 233 provide standards for the above-mentioned purposes, relative to pipes and their corresponding union nuts and union screws.
Using such parts requires suitable tools (such as wrenches) for both assembly and disassembly, so it takes a relatively long period of time to produce a dependable connection between a pipe and a hose fitting. The increased use of assembly-line manufacture and of robots, for instance in the manufacture of automobiles, requires the assembly of different individual parts in as few operating steps as possible.
Federal Republic of Germany Provisional Pat. No. AS 15 25 582 discloses a hose fitting in which a bushing is pushed over a brake hose and clamped fast by deforming the bushing. This bushing is then introduced into a corresponding counter-piece and locked axially by a U-shaped push-on clip. This arrangement has the disadvantage that precise axial positioning is not automatically obtained, but must be found by visual examination so that the push-on clip which prevents unintended loosening of the plug connection can be passed through the boreholes in the housing and engage the annular groove of the bushing. Furthermore, it is not possible to clamp the bushing firmly on a pipe without changing the cross-section of the pipe.
None of the solutions known from the prior art is therefore suitable for machine assembly of a plug-in connection.